Hydrates are solid crystalline compounds of snow-like appearance with densities less than that of ice. Natural gas hydrates are formed when natural gas components, for instance, methane, ethane, propane, isobutene, hydrogen sulfide, carbon dioxide, and nitrogen, occupy empty lattice positions in the water structure. In some instances, hydrate formation occurs at temperatures considerably higher than the freezing point of water. Gas hydrates constitute a solid solution, gas being the solute and water the solvent, where the two main constituents are not chemically bounded.
Hydrates form at specific temperature and pressure ranges that are dependent on the ratio of hydrocarbons to water and the type of hydrocarbons present. Flow assurance models are often run and analyzed to ensure that hydrate formation does not occur at a production facility.